Abstract: A high performance liquid chromatographic method for the determination of DNJ in Morus alba L. leaves withfluorimetric detection after precolumn derivatization with 9-fluorenylmethyl chlorformate (FMOC-Cl) was established. Thecontents of DNJ in Morus alba L. collected within different vegetative periods were determined. DNJ in Morus alba L. leaveswas extracted with 0.05mol/L HCI, derivatized with FMOC-Cl, and analyzed by high performance liquid chromatographyequipped with fluorescence detector. Mobile phase consisted of acetonitrile -0.1% aqueous acetic acid(55:45,V/V)with aflow rate of 1.0ml/min. The calibration curve was linear over the concentration range from 0.567μg/ml to 34μg/ml, the correlationcoefficient was 0.9999. the average recovery was 97.2%, RSD was 1.97(n=6). The results showed that the content of DNJ inleaves of Morus alba L. is relative to the vegetative periods and temperature, the highest content of DNJ in leaves of morus albaL. collected at July and August. The method used this paper was reliable, accurate and stable. It can be used for determinationof the DNJ in leaves of Morus alba L.

Key words: Leaves of Morus alba L., 1-deoxynojirimycin, high performance liquid chromatography, precolumn derivatization